TMR device with improved MgO barrier
a technology of magnetoresistive sensor and mgo barrier, which is applied in the field of high-performance tunneling magnetoresistive (tmr) sensor in recording head, can solve the problem of not treating the uppermost metal layer, and achieve the effect of minimizing metal inter-diffusion, improving bonding, and improving interfa
Active Publication Date: 2012-06-19
HEADWAY TECH INC
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Benefits of technology
The multilayer tunnel barrier structure effectively reduces the RA value to 1 ohm-μm² or less while maintaining a high MR ratio, improving device stability, signal-to-noise ratio, and extending the device's lifetime, without significant changes to the fabrication process or throughput.
Problems solved by technology
However, the uppermost metal layer is not treated with NOX.
Method used
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second embodiment
[0026]The M1 layer has a greater thickness than other M layers, and preferably greater than 4 Angstroms in order to generate a continuous metal layer free of pinholes before the first MOX layer is formed. The formation of at least three MOX layers provides an advantage over a bilayer scheme in that a more uniform tunnel barrier is produced. It should be understood that as a metal layer thickness increases, a stronger NOX dose (longer oxidation time and / or higher oxygen pressure) is required to oxidize the layer. Therefore, according to one embodiment of the present invention where relative thickness is in the order M1>M2>M3, and M3 becomes fully oxidized during an annealing step, the NOX dose for the M1 layer is higher than for M2. In a second embodiment wherein relative thickness is on the order M1>M2>M3, M4, and M4 becomes fully oxidized during a subsequent annealing step, the NOX dose for M1 is higher than for M2, and M2 NOX dose is higher than that for M3. As described in relate...
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Abstract
A method of forming a high performance magnetic tunnel junction (MTJ) is disclosed wherein the tunnel barrier includes at least three metal oxide layers. The tunnel barrier stack is partially built by depositing a first metal layer, performing a natural oxidation (NOX) process, depositing a second metal layer, and performing a second NOX process to give a MOX1 / MOX2 configuration. An uppermost metal layer on the MOX2 layer is not oxidized until after the MTJ stack is completely formed and an annealing process is performed to drive unreacted oxygen in the MOX1 and MOX2 layers into the uppermost metal layer. In an alternative embodiment, a plurality of metal oxide layers is formed on the MOX1 layer before the uppermost metal layer is deposited. The resulting MTJ stack has an ultralow RA around 1 ohm-μm2 and maintains a high magnetoresistive ratio characteristic of a single metal oxide tunnel barrier layer.
Description
RELATED PATENT APPLICATION[0001]This application is related to U.S. Patent Application Publication 2007 / 0111332; Ser. No. 11 / 280,523, filed on Nov. 16, 2005 Now U.S. Pat. No. 7,780,820; assigned to a common assignee and herein incorporated by reference in its entirety.FIELD OF THE INVENTION[0002]The invention relates to a high performance tunneling magnetoresistive (TMR) sensor in a recording head and a method for making the same, and in particular, to a method of forming a tunnel barrier layer between a pinned layer and free layer that improves reliability, decreases the resistance×area (RA) value to about 1 ohm-cm2 or less while maintaining a high magnetoresistive (MR) ratio.BACKGROUND OF THE INVENTION[0003]A TMR sensor serves as a memory element in Magnetic Random Access Memory (MRAM) devices and in magnetic read heads, and typically includes a stack of layers with a configuration in which two ferromagnetic layers are separated by a thin non-magnetic dielectric layer. In a magnet...
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IPC IPC(8): H01L21/00
CPCH01F41/307B82Y40/00H01L43/12G11C11/161H10N50/01
Inventor ZHAO, TONGWANG, HUI-CHUANLI, MINZHANG, KUNLIANG
Owner HEADWAY TECH INC